Poison not propagate through @llvm.pow[i]

[lukel97]

I believe we should be able to fold @llvm.pow[i] with a poison operand to poison:

define float @src(float %x) {
  %powi = call float @llvm.powi(float poison, i32 %pow)
  ret float %powi
}

define float @tgt(float %x) {
  ret float poison
}

But we don't do this today: https://godbolt.org/z/EGrYPc6oW

I can't think of a reason why poison wouldn't propagate, I presume it would act similarly to e.g. @llvm.sqrt which we do fold poison through.

Alive doesn't seem to support the pow[i] libcall just yet https://alive2.llvm.org/ce/z/CXcVgc

[badumbatish]

i'll give this a try

[hstk30-hw]

Maybe here
https://github.com/llvm/llvm-project/blob/main/llvm/lib/Analysis/InstructionSimplify.cpp#L6676-L6684